Good news the Sonos Arc can be ordered again and should be in stock by early April to early May according to Digitec.
Surprising that it's taking so long, it's almost impossible to buy an Arc anywhere at the moment. Sonos probably didn't expect such a big rush of orders :D.

Unfortunately, we currently have no information on when the item will be available and when we will be able to deliver it. As soon as something changes in this regard, we will post it here. Sorry.